Gas-operated self-loading firearm



Sept.' 27, 1949. H. H. SEFRIED, u

` GAS-OPERATED SELF-LOADING FIREARM 3 Sheets-Sheet l Filed Jan. 17, 1947 i um -mw om. f@ mm a ---ww g-m Qmr mm mw www? WD mmmmmmmmmmmmwm 4m H. H. SEFRIED, ll

GAS-OPERATED SELF -LOADING FIREARM Spt. 27, 1949.

3 Sheets-Sheet 2 Filed Jan. 17, 1947 I .ir/951...

Anm

Sem, 27, 1949.

H. H. SEFRIED, ll

GAS-OPERATED SELF-LOADING FIREARM 3 Sheets-Sheet 5 Filed Jan. 1'7, 1947 Patented Sept. 27, 1949 GAS-OPERATEDv SELF-LOADING Harry H. Sefried, II, New Haven,

to OInIndustri'es, Inc., corporation of' Delaware Conn., assigner l New Haven, Conn.,a

Application January 17, 1947, Serial No; 722,626

Claims. (Cl. 89-193) The present invention vrelates in general to firearms andmore especially to a self-loading repeating iirearm havingA improved gas-operated means for automatically actuating the breechblock and related mechanisms of the rearm.

An object ofy the. invention is the provision of improved gas-operated breechblock-actuating means for repeating firearms. Y Y l A further object of. theinven-tion is to provide superior*gas-operated` means wherein the breechblock and associated mechanisms are actuated by the expansion of a confined and predetermined quantity of gas derived from thedischarge of a cartridge.

A still further object-,of titel invention is to provide improved. gas-operated means for rearms embodying a member responsive both to the force of recoil of the firearm and tor gas pressure derived v from the discharge of a cartridge to admit a predetermined quantity of gasfrom the barrel of the firearm into a gas-cylinder for operating .the breechblock.

A stili further ebiect ofthe linvention is te A provide anautomatic self-loading rearm with improved gas-operated means wherein the; initial high-pressure gases: derived from the discharge of a cartridge are` dissipated actuating a valvemember which, in turn, confines a predeterminedv quantity of'gas in a gas-cylinder having a hollow piston, `the latter being adapted to be displaced by theA relatively-moderate expansion of the predetermined quantityv of gas for actuating the breechblock. y

Withi the above and other objectsin' view', as will appear to those skilled in the art from the present disclosure, this invention includes Vall features in' the said disclosure whichV are novel over the prior art.

In the accompanying. drawings, in whichV certain modes of carrying out theV present invention are shown for illustrative purposes-z Fig. 1 is a broken sidee'leva-tionof a repeating firearm: embodying the improved gas-operated breechblock-actuating.means of this' invention; the rearm being the typev whichrh'asf a fixed barrel, tubular magazine' anda compound-movement breechblock; i

Fig. 2a isan enlarged fragmentary side elevation, partly in section, oitheforward end of the rearxn shown in Fig. 1,` the elements of VtheV iinproved gas-operated breechblock-actuating.means of this invention being in theirnormal inoperativeV positionsi Fig. 2b is an enlarged fragmentary side elevation. partly in section.,` ofthe rear end portion'of 55 the iirearm of Fig.. 1, showing the breechblock locked in breech-closing position.;

Fig. 3 is a sectional elevationon line 3-3 of Fig. 2a showing the forward barrel-bracket and the continuous gas-passage communicating with the bore of the barrel andthe piston-chamber vof the gas-cylinder; Y

Fig. 4 is a sectional elevation Vvon line 4 4 of Fig. 2a showing the transverse key for connecting the rear end Fig. 5 is a fragmentary side elevation, partly in section, similar to Fig. 2a.v but showing the forward position of the sleeve-valve of the gasoperated means immediately following the discharge of a cartridgev in the barrel of the firearm;

Fig. 6 is similar to Fig. 5 showing the hollow piston in its rearmost position in the chamber of the gas-cylinder, due to theI expansion of a predetermined quantityof gas therein;

Fig. 7 is a fragmentary plan view on section line l-'l of Fig. 2a showing the annular collar which connects the forward end' of the actionreturn spring tot the laterally-projecting key of the hollow piston;

Fig. 8 is a perspective view of a gas-cylinder of the gas-operate'd breecliblock-actuating means of this invention;A Y

Fig.. 9 is a perspective viewer the hollow piston adapted to be. sli ably mounted in the chamber of the gas-cylinder shewn Fig. 8;

Fig. k is a perspective view of the sleeve-valve adapted to be mounted in the forward end of the piston-chamber either gas-cylinder to admit a predetermined quantity ci gasirom the barrel of the iirearm into the piston-chamber for actuating the hollow piston; and

Fig.. 1I. is a perspective view of the Aannular collar whichl connects the Vhollow piston to the action-return spr-ingrr The particular gas-operated self-loading rearm herein chosen for' the purpose of illustrating one form of the"present; invention includes', in the main',4 a stock t5 to the forward end of which is secured: a receiver' lie within: which a breechblock I'l mounted formovement. to and from breech-closing: position, the breechblo'ck l1 being of thel compound-movement type having a locking-lug I8 at its rear endv adapted to engage in. a notch t9 in'. the underside oi the top wall' of the receiver to' lock4 the bre'echblock in breech'- closing position, the breechblock being actuated by' an action-Sden having ating. 2| at itsrear end adapted. tov cammingly engage in a cam-slot 22 in the side of the breechbl'ock. A more corn'- pletel description of the coaction of the actionof the piston` tothe action-slide;

slide lug 2l and the cam-slot 22 of the breechblock for effecting the compound movement of the latter is given in the Johnson Patent No. 958,407 dated May 17, 1910. Briefly, however, it may be recalled that by moving the action-slide 2E] rearwardly, the rear end of the breechblock is swung downwardly, thereby drawing the lockingfv lug I8 out of locking-engagement with the locking-notch I9 Vofthe receiver, the breechblock I'i being moved thereafter rearwardly in the receiver,A to open the breech and eject a fired cartridge from the ejection-port 23 ingthesidefof their@- ceiver. By the subsequent forward movement of the action-slide, the breechblockl IfIjis-movedand' th'en swung upi' forwardly in the receiver wardly into breech-closing position, in which position it is locked by engagementlof the locking, lug i3 in the notch I9 of the receiven During the forward movement of the breechblock, suitable loading-means (notshown) is adapted to be actuated to automatically relevate a cartridgeI from the tubularmagazine 24 of the rearm into the breech 25 of the barrel.- The trigger and firing-mechanism of the firearm Aare/indicatedY generally at 26 in Fig. l and inasmuch as these elements do not constitute a part of the present invention, a more detailed description thereof is unnecessary here.

The barrel 21 of the firearm is adapted to be secured by an interrupted-thread connection 28, of conventional Yconstruction in an' interiorlythreaded aperture in the 'forward end of the receiver. Supported-on the rear end of the barrel immediately adjacent-thefrontc face of the re ceiver, is a barrel-bracket indicated generally at 29, the upper portion 'of which is formed with a cylindrical passage' 30 in which the adjacent rear portion of the `barrel snugly ts, vthe barrelbracket being 'removably secured. toV the barrel by suitable fastening-means Anot shown. .The

lower portionof the barrel-bracket constitutes an.;v integral forwardly-extending -cylindrical sleeve 3|, the longitudinalll'axis v7of :which ,is substantially parallel to and in the vertical-plane ofthe longitudinallfaxis'. of. the barrel MThe rearrlerid of the sleev'esS'If abuts the front lfaceyofk the-ref ceiver, which, as shown clearly inlFi'g. 2b, is.pio' v vided witha cylindrical. aperture 132 the .longitudinal axis of which .is in alignment with .the longitudinal axis ofthejlcylindrical ,aperture 33y of the sleeve 3l; The latter 1isof .a diameterl to receive` and support the' rean end of Athe tubularA magazineI 24,th'e reari end of`whichmakes a snug fit in the-sleeve-'aperture `33. Moreover, the rear extremity of the magazine 24A is adapted toexvv tend through thesleeye lxandmake a snugty in the axiallyaligned aperture 32 in 4the front face of thevreceiver.. vlormedgintegrally and uex: teriorly on the tubular magazineis anannular flange 34 which, when the tubular magazineis assembled inthe axially-aligned apertures of the receiver and barrel-bracket 29,v abuts the forward end of thebracket-sleeve 3.I and constitutes a limit-stop to prevent the tubular magazine froml moving rearwardly; in: ,the barrel-bracket sleeve v 3l. The forward face of .theannular flange VV34. constitutes a lflxedshoulder against whichxzthe rear end of the-action-return spring 35 is adapted to seat, the action-returnspringlbeing supported` on the forward end of Athe tubular magazine, as shown clearly, in. Fig. 1.,- Fixedly secured in the. forward end of the tubular magazine-.is a plug constituting, for eXample,'a;1cup-shape'd member 36 (seevligsZoL) in which-the forward end of the follower-spring;31 ofi the cartridge-load- G52 wiardly,Y in the bushing 4 l 5 the firearm in the well known and customary manner. Mounted on the forward end of the barrel 21 and secured thereto by a rwelded joint or equivalent fastening-means, is jajsecond barrel-bracket, indicated generally 'atv 39 inV Figs. 2a

,and 3, the upper portion of the bracket being formed with a cylindrical aperture 40 in which 'the forwardsend of the barrel snugly ts. The lower portion of the bracket constitutes an integral cylindrical bushing 4I having a cylindrical if. aperture 42, therlongitudinal axis of which is substantially parallel to the longitudinal axis of the barreland in .alignment with the longitudinal axis of the tubular magazine 24. Referring to Fig."3,' the upper and lower portions of the barrelg bracket 33 are joined by an integral constricted neck-portion '43 in which is formed a vertical aperture orgas-passage 44, the upper' end of which intersects the cylindrical aperture 40 in the upper portion ofA the bracket Vand the lower end -of which intersects the cylindrical aperture 42 in the lower portion ofthe bracket; Moreover, as assembled on*thelbarrelgthefupper end of the gas-passage 44 `i`s-fsubstantially opposite f and in direct communication with a radially-exd tending aperture --whichis vformed in the underside ofthe barrel and Iintersects the bore 4tv thereof. l

The cylindrica1 lap' rturev 42 'of' the barrelbracket bushing 4| is adapted to support the forend of a gas-cylinder in-dicated generally lat 41 and which, as shown in Figs. 2a and 8, compri-ses a substantially#cylindrical tube having a short length 4810i reduced diameter at its rear end, the rear extremityV of which is adapted to 2'1" maken-snug fit in the forward end'o'f the tubular magazine 24, whereby the' rear end of the glascylinder 4l is supported thereby. The forward end of the-gas-'cylinder` 412 isprovicledI with exterior threads 49which, when the cylinder is asili" sembled'tin the barrel-bracket bushing 4I, are in juxtaposition to'theannular rear shoulder of the latter.- Threadedly4 engagedwith the threads 49 of Vthe,gas-:cylinder` is.-.an.` annular locking-ring 50 which is adapted tolbeturned lurp'ron the threads 59S 49 and by eng-agement .wit-htheannular rearwardly-f-acing..shoulderof.,the bushing 4 I, to draw the gas-.cylinders.46'rearwardly therein,y so ,as to hold the rear end 48 of the gras-cylinder securely-in the forwardnd lof, the tubular maga- 552. zine 24. A'Iherearwardlmovement of the gas-cylinderin the bushing. 4.'I is limited byimeans of anannular flange.. kElssformed,V integrally at the forward end of the cylinder, .therearwardlyfacing shoulder ofthey angei I` being adapted to Gili-be vbrougl'it into abnttingengagement withl the forwar-dlyef-acing shoulder .ofllthe bushing 4I by turning up .the locking-ring 50. V1n this manner, thelgas-cylinder 41, is rmlyjsecured against longitudinal displacement, both forwardly 'and rear-` ;Referring again to Figs. 2a and 8, the.gasvcylinder 41 is shown provided with a gas-port 52 which constitutes a relaltively-narrow transverse. .slotin the upper side of thegas-.cylinder 4]the slot fbeing a preferred '7.0; constructionV to facilitate`-lassembly of the gascylinder in the barrel-'bracket bushingM and tubular magazine llbfthe'rearm. As assembled by the aforesaid members on the underside of the barrel ofrthelrearmdh'e gasfpont 52 of the gasl75 cylinder 41 is .substantially opposite and in direct communication with the lower end of the'vertical gas-passage 44 at its point of intersection with the cylindrical aperture 42 of the bushing 4I, whereby an unobstructed passage exists be tween the bore 46 of the barrel and the interior or piston-chamber 53 of the gas-cylinder 41. FormedY in yopposite sides of the gas-cylinder in a substantially-horizontal plane parallel to the longitudinal axis thereof, is a pair of longitudinal -guide-slots 54, the opposite ends of each slot being closed Iand the rear end of each slot terminating a short distance forwardly'of the rear extremity 48 of the gas-cylinder. The over-all length of each guide-slot -54 bears a specific relationship to the length of the gas-piston hereinafter described and in the present embodiment is slightly less .than one-half the effective length of the gas-cylinder.

Slidingly supponted in the piston-chamber 53 of the gas-cylinder 41 is a gas-piston indicated generally at 55 (see Fig. 9) comprising a hollow cylindrical tubular body-portion 56 open at its forward end but closed at its rear end by an integral solid head-portion 51 having a cylindrical bearing-surface 58, the diameter of which corr-esp-onds to the internal diameter of theV pistoncham'ber 53,.whereby the cylindrical bearing-surface 58 is adapted to slidingly support the rear end -of the hollow piston therein. The forward end of the piston is provided with a similar cyf lindrical bearing-surface 59, the diameter of the latter also corresponding to the internal diameter of the piston-chamber 53 for slidingly supporting the forward end of the hollow piston.

The body-portion 56 of the piston intermediate the rear and forward bearing-surfaces 58 and 59 respectively is preferably of slightly-reduced diameter to provide clearance between the main body-portion of the hollow piston and the vwall of the piston-chamber 53, as clearly shown in Fig. 2a. As shown in Fig. 9, the head-portion 51 of the hollow-:piston is provided with an integral rearwardly-extending tongue-portion 60, the longitudinal axis Iof which is in -alignment with the longitudinal axis of the piston, the tongue 60 being substantially-rectangular in cross section except that its diametrically-opposite sides 6| are cylindrical surfaces of revolution. Extending transversely through the tongue v6l] in a horizontal .plane .and intersecting the opposite cylindrical sides 6| thereof, is an aperture 62 substantially-rectangular in cross section, the longitudinal'axis of the aperture 62 intersecting the longitudinal axis of the hollow piston at substantially right angles. The transverse substantially-rectangular aperture 62 in the tongue 60 of the hollow piston is adapted to accommodate a transverse key 63 which is substantially rectangular'inrcross section and adapted to make a snug t in the transverse aperture "62. The key 63 may be secured in the aperture 62 from lateral displacement therein by means of a spring-pressed retaining-pin 64 which, as shown in Fig. 2a, is mounted in a longitudinal .axial aperture 65 of the piston-head 51, the rearwardly-extending end of the aperture 65 intersecting the front wall of the transverse aperture `62. The retaining-pin 64 is urged outwardly or rearwardly into the rectangular aperture 62 by a spring 66 seated in the bottom of the aperture 65 and engaging at its rear end against the forward end of the retaining-pin 64. The rear end f the retaining-pin is reduced indiameter as at `61 and adapted to engage in an aperture 68 intermediate the opposite ends of the transverse key l63 and at substantially right langles to the longitudinal axis thereof. For assembling and disassembling the key in and from the transverse aperture 62 of the piston-head, a longitudinal axial aperture "69 is provided in the tong-ue 60 intersecting thetransverse aperture 62 thereof and in axial alignment with the spring-pressed retaining-pin `64, whereby a drift-pin or similar device may be inserted through the aperture 69 into engagement with the reduced end 51 of theretaining-pin 64 to displace the latter forwardly, out of engagement with the aperture `68 of the key =63 and hence permit the latter to be withdrawn from the transverse aperture 52.

Referring to Fig. 1 and looking in the direction of the gun-muzzle, the right-hand end'of the keir 63 is adapted to extend through the corresponding guide-slot 54 of the gas-cylinder 41, the thickness of the extended end of the key corresponding substantially to the width cf the slot so as to make a smooth sliding fit therein. The outer extremity of this extended end of the key is provided with an enlarged substantially-rectangular head 10, the inner curvilinear flanges 1| of which are adapted to slidingly engage the exterior circumference of the gas-cylinder 41, as shown in Fig. 4. A hole 12 is drilled or otherwise formed substantially'verticaliy through the enlarged head-portion 16 of the key for securing an annular collar 13 thereto, the latter being provided on its righthandside with a pair of integral forwardly-extending spaced parallel fingers 14 (see Fig. 11) adapted to extend over the top and bottom sides respectively of the enlarged head-portion 16 of the key, as shown in Fig. 4, and to be secured thereto by a pin 15 which is inserted into suitable axially-aligned apertures 16 in the ends of the fingers 1| and in the hole 12 of the key-head 163. As shown in Figs. 2a and 7, the annular collar 13 has a sliding t on the rear end of the gas-cylinder 41 and is provided in its rear face with an annular recess 11 which is semicircular in cross section` and constitutes a seat for the forward end of the action-return spring 35. The opposite end of the key 53 is also extended laterally so as to provide an end portion adapted to slidingly engage in the corresponding longitudinal guide-slot 54 of the lgas-cylinder 4l, this left-hand end portion of the key terminating at its outer extremity in a cylindrical lug 18. The latter is adapted to have locking engagement in a suitable aperture in the forward end of the action-slide 25 whereby the hollow piston 55 is positively connected to the breechblock I1.

Referring to Figs. 2a and 10, mounted in the forward end of the piston-chamber 53 of the gascylinder 41 is a sleeve-valve indicated generally at 89. The latter comprises a tubular member of relatively-thick wall section provided between its opposite open ends with a substantially-solid integral transverse wall or partition 8l located nearer the forward end of the sleeve-valve than the rear end thereof, as shown clearly in Fig. 2a. Formed in the top side of the sleeve-valve immediately to the rear of the rear face of the partition 8i, is a transverse slot or gas-port 32 which is adapted normally to lie substantially opposite the gas-port 52 of the gas-cylinder 41, the gas-port 82 of the sleeve-valve being substantially twice the Width of the latter to facilitate adjustment and provide for the admission of a measured quantity of gas into the gas-chamber, as hereinafter described. The partition 8l is provided with an axial aperture 83 in which is riveted or otherwise secured the reduced rear vend 84 of a valve-stern 85, the

forward-onder shank 86 of whichzis hexagonal in crossysectionfor` the purpose hereinafter, described. The shank 86 of the valve-stem is terminated at its forward end by a cylindrical externally-threaded shank-portion 81 of reduced diameter. Mounted in the forward open end of the sleeve-valve 80 with its rear end seated Aagainst the forward face of thepartition Sliandencircling the valve-stem 85, is a coil valve-spring 88, the forward end of which is adapted to seat in the counterbore 89 of a cap 98 which is threadedly secured and normally held from rotating inthe forward open end ofthegas-cylinder 41, the cap 90 having an axial aperture 9| which is in axial alignment with the hexagonal shank 86 of the sleeve-valve and hexagonal in shape to slidingly accommodate the latter, the hexagonal surfaces o f the valve-stem shank 86 and of the aperture 9| in the lixed cap 90 normally coacting to prevent rotation of the sleeve-valve 8l). An adjusting-nut 92 having a flanged base-portion 93 is adapted to be threadedly engaged on the forward threaded end 81 ofthe valvestem to hold the sleeve-Valve. in a normal predeterminedzposition in the yforward end'of the gas-cylinder, wherein A the gas-port 82 of the sleeve-valve is substantially opposite the gas-port 52 of -the gas-cylinder and hence in direct communication with the bore 46 of the barrel byway of the axially-aligned gaspassage in the bottom of the barrel. The adjusting-nut 9.1iY is adapted to'be locked in adjusted position by a locking-nut 94. It willbe clear that by turning the adjusting-nut v92, the sleeve-valve may be drawn forwardly against the resistance of the springv -88 or releasedl and moved rearwardly by the force of the partially-compressed spring 88; and that whereas the nal adjustment of the nut 92 will limit the rearward movement of the sleevevalve in the piston-chamber 53 of the gas-'cylinder 41, the sleeve-valve 89 may, ,'neyertheless; move. forwardly therein, the only resistance .to its,for` wardmovenrent being the force required Y:tozcornpress the valve-spring 88. Topreclude a ,dash pot effect in the gas-cylinder between the forwardr` end of the sleeve-,valve and the rear end of the cap 90 as the valve movesforwardlyptherein the cap 90 Yis proyidei` with a plurality of vents 95, the outer ends of which are normally covered by the flanged base '93- of the adjusting-nut 92 but are adapted to l be. immediately inricovered to release any entrapped. air or gas a,s;;t1l'1esleeve-Y valve begins to move forwardlyin thegas-cylim; der, as hereinafter described. d 3.

The operation ofthe firearm may b e described briefly as follows. With acartridge in .the breech 25 vof the barrel and the -breechblock-H locked in breech-closing position, as shown :in Fig. 21),-, and the elements of they gas-operated breechblook-actuating;mechanismrin'their normaiposie tion, as shown in Fig.; 2a thenwhen etherjcarfV tridge is` red, ,the .immediata-.effect `"of *itsafdisa charge `vwill be the deyelopmentof alarga-volume of gas under high nressurefwthinthe-bore .45; ofVv the barrel. Thisg high-pressure;` gas drives; the projectiledown the. bore .of -theg-barrel and .when the gas is oppositerthe gas-port 45 ytherein, .it escapes substantially immediately: by,zway-.of the gas-port 45, :the gas-passage. i: the;fbarnelbracket 39 and; the aligned 4.gas-ports 5.2 and182 of the gas-cylinder, 41;:and ,thefsleevevalve 18|)4 respectivelyA into the;lpistonchamberzt53erof -the gas-cylinder, substantially ;instantaneonsly.rilling therhollow bodyeportioni56for-theepiston 55 and the open-rear Lendfof thegtubularrsleexLe-valve 44 of the bracket 4I and the Agas-port 45 The pressure ofthis gas acts with substantially equal force against the closed end of the. hollow piston and the partition 8l oirthe Sleeve-valve, but since the valve-,spring- 88 is considerably lighter than the Vheavy action-return spring 35 of the hollow piston 55 the latterY will remain immobile whereas thev sleeve-valve will be thrust forwardly until its front end strikes the rear end of the cap 90. Consequently, the valve-spring 88 will be compressed and the gas-port 82 of the sleeve-valve will be moved out of registration with the gas-port 52 of the gas-cylinder so as to effectively shut ofi the piston-chamber of the gas-cylinder from the bore 48 of the barrel and hence prevent the admission of additional gas from the, latter into the piston-chamber. In addition to the force which is applied to the sleeve-valve by the high-pressure gas, the inertia ofthe sleeve-valve on recoil of the firearm will displace the valve forwardly also relative to thegas-cylinder 41 and other xed parts of the firearm; Thus, by the combined forces of recoil and gas pressure, the'sleeve-Valve is movedV from its normal position in the chamber of the gascylinder, as shown in Fig. 2a, to its advanced or cut-off position, as shownin Fig.5. As pointed out above, as the sleeve-valvebegins its forward movement, the base 93 of the adjusting-nut 92 uncovers the vents 95 inthe cap 90 so as to preclude any dash pot effect between'the cap and theforward end ofthe sleeve-valve. Immediately following the arrival of the sleeve-valve in its cut-off position and the consequent prevention of the admission of -additional gas from the bore of the barrel into the piston-chamber, thisY confined and predetermined quantity of gas inthe chamber begins to expand, and since further movement of the sleeve-Valve is prevented by engagement with the xed cap 90, thereby to displace the hollow piston rearwardly in the piston-chamber of the gas-cylinder, overcoming the resistance oiered b y compression of the action return-spring 35. As the hollow piston moves rearwardly, its connection with the action-slide 20 serves tovmove'the latter rearwardly and hence to unlock the breecnblock and carry it rearwardly in the receiver to effect the extraction and ejectionof the fired cartridge. As the piston approaches its rearmostl position in the pistonchamber, the cylindrical bearing-surface 59 at theforward end of the piston uncovers the forward ends of the longitudinal guide-slots 54 in the sides of the gas-cylinder 41. These uncovered portions of the longitudinal guide-slots 54 thereupon act as exhaust-ports from which the gas within the piston-chamber 53 of the cylinder escapes to the atmosphere, as indicated in Fig. 6. As soon as the gas pressure within the chamber has been reduced below the force required-,1 tol hold the -sleevefvalve spring 88- corn-y pressed,.the latter, acting against the partition fila-of the sleeve-valve, returns the sleeve-valve rearwardly in the piston-chamber of the gas-cyl-` inder. to its normalposition,-wherein its gaspport 8-2 registers with the gas-passage tothe bore of thebarrel. At substantially the same time, the force of the compressed actionreturn-spring 35, acting against theannular collar 13= of the piston, moves the piston forwardly inf'the' gasp-cylinder andttherebythrough the actionrslide which connects the piston to the breechblock, 'to pull 'the latter forwardly into,breecheclosingposition. As the` piston 4movesforwarclly: in :the fp iston-chame ber, :theirn ward lends 10i, .the longitudinal guidefi slotsetlof:theigas-.cylinder:areclosed,mutinase muchas thegas-port 82 of the sleeve-valve is now in registry with the gas-passage to the bore ofthe barrelL any air orgas which may be trapped in the chamber between the piston and the sleeve-valve, is kenabled to escape through the gas-passage into therbore of the barrel and so to the atmosphere. Thus, any dash-pot action within the piston-chamber 53 is prevented and the hollow piston islpermitted to move forwardly freely to its normal advanced position therein, as shown in Fig. 2a. The various elements of the gas-operated breechblock-actuating means are again in normal position for operation when the next cartridge is fired.

Although omitted for the sake of clarity, it will be understood that the firearm shown, like similar types of gas-operated guns, may be provided witha forestock adapted toenclose the gas-cylinder and action-return spring.

It will be manifest from the foregoing description that the initial high gas pressure is not used directly to actuate the piston and actionslide for operating the breechblock but is dissipated in actuating the slide-valve, the actuation of which cuts 01T the passage of gas from the barrel to the gas-cylinder and confines a predetermined quantity of gas therein. It is the expansion, at a relatively-,modified rate, of this confined and predetermined quantity of gas within the piston-chamber of the gas-cylinder which effects the actuation of` the breechblock, thereby precluding any sudden and severe blows on the action-mechanism.v Y

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, andthe present embodiments are, therefore, to be considered in all respects (as illustrative and not restrictive and all changes coming withinv the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim: 4 l

1. A gas-operated self-loading firearm, including in combination: a receiver; a barrel secured to the forward end of said receiver; a breechblock mounted in said receiverv and movable therein to and from .breech-closing position; and gasoperated means for actuating said breechblock, comprising a gas-chamber in communication with said barrel, a first gas-operable member in said gas-chamber, said first gas-operable member having a connection with said breechblock, and a second gas-operable member in said gas-chamber arranged to admit a predetermined quantity of gas from said barrel into said gas-chamber to operate said first gas-operable member.

2. A gas-operated self-loading firearm, including in combination: a receiver; a, barrel secured to the forward end of said receiver; a breechblock mounted in said receiverY and movable therein to and from breech-closing position; and gas- ,operated means for actuating said breechblock.

comprising a gas-chamber in communication with said barrel, a first gas-operable member in said gas-chamber, said first gas-operable member having a connection with said breechblock, and a second gas-operable` member in said gaschamber arranged to admit a predetermined quantity of gas from said barrel into said gaschamber on discharge of said firearm and thereafter to cut off the admission of gas to said gaschamber so as to confine said predetermined quantityl of gas thereinV for operating said firstgas-operable member.-

3. A gas-operated self-loading firearm, including in combination: a receiver; a barrel secured to the forward end of said receiver; a, breechblock mounted in said receiver and movable therein into and out of breech-closing position; gas-operatedmeans for actuating said breechblock, said gas-operatedmeans comprising a gascylinder having a piston-chamber communicating with the bore of said barrel, a piston slidably mounted in said piston-chamber, and a sleevevalve in said piston-chamber actuated both by gas pressure and the recoil of said rearm to admit a predetermined quantity only of gas from the bore of said barrel into said piston-chamber to actuate said piston; and an action-slide connecting `said first piston to said breechblock. 4. A gas-operated self-loading firearm, including in combination: a receiver; a barrel secured to the forward end of-said receiver; a breechblock mounted in saidi receiver and movable therein into and out of breech-closing position;

.gas-operated means for actuating said breechblock, said gas-operated means comprising a gascylinder having a Apiston-chamber provided with a gas-port communicating with the bore of said barrel, a piston slidably mounted in said pistonchamber, and a gas-operated sleeve-valve mounted resiliently in said piston-chamber, said sleeve-valve being resiliently held normally opposite the gas-port of said piston-chamber and arranged to be displaced therefrom following the discharge of saidfirearm to close said gas-port so that a predetermined quantity only of gas is admitted from the bore of said rbarrel into said chamber to actuate said piston; and an actionslide connecting said piston to said breechblock.

5; A gas-operated self-loading firearm, including in combination: a receiver; a barrel secured tothe forward end of said receiver; a breechblock .mountedin said receiver and movable therein into and out of breech-closing position; a tubular magazine supported at its rear end by said reciver on the undersideV of. said barrel; gasoperated means supported on the underside of said barrel for actuating said breechblock, said gas-operated means comprising a gas-cylinder having a piston-chamber communicating adjacent-one end of said gas-cylinder with the bore of said barrel, saidv gas-cylinder being reduced at its opposite end to t in the forward end of said magazine so as to support the latter in alignment therewith, a piston slidably mounted in said piston-chamber, means to admit a predetermined quantity only of gas from the bore of said barrel into the said piston-chamber to move said piston rearwardly in said chamber; resilient-means mounted on said magazine, said resilient-means .including a member slidably mounted on the rear end of said gas-cylinder and connected to said piston to return said -piston to its forward posi- `tion'in said chamber; and an action-slide connecting said piston to said breechblock.

' 6. A gas-operated self-loading firearm, including in combination: a receiver, a barrel secured to the forward end of said receiver; a breechblock mounted in said receiver and movable therein into and out ofbreech-closing position; a tubular magazine supported at its Vrear end by said re- -ceiver on the underside of said barrel; gas- 'operated means supported on the underside of `said barrel for actuating said breechblock, said gas-operated means comprising a gas-cylinder having longitudinal gas-exhaust ports and a piston-chamber, said piston-chamber communieating adjacent one end of said gas-cylinder with lpiston-chamber ymember slidably mounted port of said rpiston-chamber toont-offA underside@ f of saidr barrel' the bore of s aid barrel, said gas-cylinder being reduced` at its opposite Yend to t in the forward end of said magazine so as to support the latter in alignment therewith, piston slidably mounted in said piston-chamber and having av key slidable in a gas-exhaust port of said cylinder, means to admit a predetermined quantity 'only of gas from the bore of said-barrel into the said'piston-chamber to move saidfpiston rearwardly 4in said chamber, said gas-exhaust ports being arranged to release said predetermined quantity of gas in said following the rearward movement of said piston; resilient-means mounted on said magazine, said resilient-means including a on the rear end of said gas-cylinder and connected to said pistonkey to return said piston to its forwardposition in said chamber; and an action-slide connecting said piston to said breechblock.

7. A gas-operated self-loading firearm, including in combination: aurceiver; .a barrel secured to the forwardlend of said receiver; a breechblock mounted in' Asaidr'cceiver and movable Y therein into Y.and yout-ofY'breech-elosing position;

a tubular-magazine supported at its rear .end by saidvrec'eiver.'nfthe'underside of said barrel; gasoperated means supported on the' underside of said barrel for" actuating 'said 'brechblocm said gas-operated meanscomprising a gas-cylinder having longitudinal `gas-exhau'stports and a piston-chamber;- said-laiston-chamber being provided with awgas-portl'adjacetfits 4forward end communicating with'thebo'r'e of said barrel, said gas-cylinder bengireducedat itsopposite end to lit in theforward'end. flsaidmagazine so as to support the latter fini-alignment therewith, a

pistonl slidably mountedlin said piston-chamber and-*havingv a key slidable in a gas-exhaust port of :said 'cylinder;.\agas-.operatedsleeve-valve mounted in said. piston-chamber, said sleevevalve being cooperatively;associated withvthe gasthe'admission of gas into saidfchamber frornsaid kgas-port and henceJto admit a predetermined 'quantity only of `gas from thebore -ofasaid barrel into said 'piston-'chamber tomove-said-pis'ton rearwardly in lsaid chamber, the-'said gas-exhaust ports insaid vcylinder being' arranged to Vrelease s'aidr predetermined quantity oigas in saidpiston-chamber following the rearward movement ofsaid piston;

'resilient-means mounted-on' said -magazine, said 'resilient-means including vamember slidably mounted on the rear end of -fsaid gas-cylinder and connected to said piston-keyftoreturn said piston to its forward position Ain`saidl chamberfollowing the exhaustion ofgas therefrom; and an actionslide connected ai? one 'endf-to said piston by said key and` at its fopposite -'nd to said breechblock.

8. A gas-operated self-loading firearm, including in '.combination: La' receiver; av-.barrel-v secured Vto the forward end of said receiver; a breechblock mountedr in"said.` receiver and movable therein into-and outof breech-'closin'g-position; a tubular magazine supportedeon' the-underside of said barrel; agas-operatedfmeans supportedon the 6 "fori actuating said breechblock, said' gas-'operated means 'comprising -a gas-'cylinder having apiston-chamber provided with a gas-portV adjacent its forward end communicating with the bore of said barrel, the rear end of said gas-cylinder being telescopingly supported in the forward. end of said magazine, said gas-cylinder having' a longitudinal guide-slot in one wall intermediate the opposite ends thereof,

a hollow piston slidably 'mounted in said pistoncylindrical sleeve?4 a chamber and having alaterally-projecting lug at its rear end adapted to slidably engage in the longitudinal' guide-slot of said cylinder, a sleevevalve mounted in the forward end'of said pistonchamber, vsaid sleeve-valve being cooperatively associated with the gas-port of said pistonchamber and arranged to be' actuated by the gas pressure Vtherein following' the discharge ofsaid rearm to c'ut off further' admission of gas into said chamber from said gas-port and hence to Vadmita predetermined -quantity only'of gas from the bore of said barrel into said piston-chamber, said gas being adapted to expand within the hollow piston to vmove the latter rearwardly in said chamber, said hollow piston beingV arranged to uncover said longitudinal guide-slot adjacent the end of its rearward excursion to release the predetermined qua'ntity o f gas in said-chamber; and a spring supported-'on-said magazine constructed 'and arranged to be cmpressed during the rearward movement of said piston and to return said piston to -its' forward"'positior'i'`A insaid chamber following the release bf g'asfro'm'said chamber; and an action-slide'connectr datone endto said piston-lug and atitspposit block. Y ,7, i

9.' A gas-operatedl self-loadi: r'earm, includiifi'g in Ycombination:l a"'r'eceiv'e`r,v a barrel secured to the forward end of saidreceiver; V a breechblock mounted in said receiver andf movable therein into and out of breech-'closing' position; a magazine-supporting bracket secured "to said barrel adjacent the rear end thereof and comprising a d tubularm'agazine slidably mounted in said'cylindrical'sle'eveof said supporting-bracket,'said magazine having a collar secured thereon adapted to abut the vforward end of said cylindricalf'sleeve'to restrict the rearward movement of saidmagazine therein; a supporting-bracket secured toy said barreladjac'ent the Aforwardend thereof; lthe second supportingbracket comprising 'a 'cylindrical bushing having a gasport communicating with the bore of said barrel; a' gas-cylinder supported-at 4its forward end in said cylinder bushing and at its rear end in the forward 4end of vsaidtubular magazine, said gas-cylinder having a` longitdinalg'uide-slot in one wall thereof and comprising a'pist'on-chamber'having an aperture at its forward end OP- posite the gas-port of Vsaidv cylindrical bushing whereby gas within ther'bfre of said barrel'may be delivered inton said pistn-chamber, a hollow piston slidably mounted -in lsaid piston-chamber, said piston having 'la laterally-projecting lug at its rear end adaptedto 'slidingly engage in the longitudinal guide-slot of said cyliri'derjclsure-means in the forward` endy o f vsaid piston-chamber comprising an apertured-c'apfa gas-operated sleevevalve slidably mountedin theforwardV end of Said piston-chamber; said sleeve-valve having a valvestem slidably mountedv the aperture of said cap and an'aperturei oneiwall 'of'sai'd sleeve-valve arranged normally substantially opposite the gasport-"of'saidf`piston-'chamber whereby-gas is admitted into saidpisto'n-cliamber-ndischarge ol said'ireaim, said sleeve-valve'being arranged'to 75 rearwardly in said piston-chamber and open said i 'end' to' 'the breechbreech, said rearwardly-moving hollow piston being arranged subsequently to uncover the rear end of said longitudinal guide-slot in said gascylinder thereby to exhaust the gas from said chamber, and Vresilient-'means to return said sleeve-valve to its original port-opening position following the exhaustion of gas from said chamber; resilient-means supported on said tubular magazine constructed and arranged to be compressed by the rearwardly-moving piston and to move said piston forwardly following the eX- haustion of gas from said chamber to close said breech; and an action-slide connected at one end to said piston-lug and at its opposite end to said breechblock.

10. A gas-operated self-loading rearm, including in combination: a receiver; a barrel secured to the forward end of said receiver; a breechblock mounted in said receiver and movable therein into and out of breech-closing position; gas-operated means supported by said barrel for actuating said breechblock, said gasoperated means comprising a gas-cylinder having a piston-chamber communicating with the bore of said barrel, a piston slidably mounted in said piston-chamber, means in said chamber arranged initially to admit a predetermined quantity only of gas into said piston-chamber on discharge of said rearm and subsequently tocut off the com- Y 2,424,264 munication between the bore of sald barrel and 30 said chamber following the discharge of said lirearm so as to confine said predetermined quantity of gas in said chamber, said predetermined quantity of gas being adapted thereafter to expand and move said piston rearwardly in said chamber; resilient-means arranged to actuate said gas-admitting means following the rearward movement of said piston in said chamber to reestablish communication of said piston-chamber with the bore of said barrel; an action-slide connecting said piston to said breechblock to move said breechblock out of breech-closing position; and resilient-means cooperatively associated with said piston to return said piston to its forward position in said chamber and thereby to move said breechblock forwardly into breech-closing position.

HARRY H. SEFRIED, II.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 877,657 Mason Jan. 28, 1908 954,797 Hammond Apr. 12, 1910 2,409,225 SchaichV Oct. 15, 1946 Yorks July 22, 1947 

